Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H, W = map(int, input().split())
l = [list(input()) for _ in range(H)]

from collections import deque
q = deque([(0, 0)])
d = [(1, 0), (-1, 0), (0, 1), (0, -1)]
l[0][0] = 0

while q:
    y, x = q.popleft()
    for dy, dx in d:
        if 0 <= y+dy < H and 0 <= x+dx < W and l[y+dy][x+dx] == '.':
            l[y+dy][x+dx] = l[y][x] + 1
            q.append((y+dy, x+dx))

try:
    g = l[H-1][W-1]
    total = 0
    for _l in l:
        for i in _l:
            if i != '#':
                total += 1
    print(total - g - 1)
except:
    print(-1)